A patient suspected of having a bacterial infection is often treated with antibiotics before the bacteria has been isolated and identified. However, this practice can complicate the diagnosis and treatment of the infection since antibiotics prevent the growth of bacteria in ordinary culture media used for the isolation of bacteria. Nevertheless, antibiotics must be given prior to isolation of the bacteria in life threatening situations when the presence of bacteria in the blood (bacteremia) is suspected. In addition, there are certain medical conditions in which it is necessary to know whether a bacterial infection persists even though the bacteria is known to be sensitive to the antibiotic. This can occur, for example, when there is a chronic source of infection such as an abscess or an infection of a heart valve (bacterial endocarditis). Therefore, a method for isolating bacteria from the blood and other body fluids containing antibiotics is desirable.
Conventional methods of identifing the presence of bacteria in the blood and other body fluids containing bacterial inhibitors have proven to be ineffective. Prior methods of inoculating culture media with specimens containing bacterial inhibitors and then determining the presence of turbidity, which indicated bacteria growth, take as long as 14 days because the presence of the bacterial inhibitors hindered the growth of the bacteria, delaying isolation and identification of the bacteria.
A method presently utilized by researchers and physicians to identify and isolate bacteria in body fluid specimens containing bacterial inhibitors involves the use of a detergent-treated resin which selectively removes antibiotics from bacterially infected body fluid specimens without removing the bacteria, see for example U.S. Pat. No. 4,145,304. By removing the bacterial inhibitors while sparing the bacteria, the system disclosed in U.S. Pat. No. 4,145,304, allows the bacteria to be cultured and identified.
Devices or systems which utilizes the resin and method disclosed in U.S. Pat. No. 4,145,304 to remove antimicrobials from body fluids are available commercially. However, utilization of such a device or system involves several steps which limit its practical usage. Generally, the body fluid specimen must be aseptically added to the device or system and then rotated continuously for 15 minutes in order for the resin to absorb the antibiotic. Then, the supernatant mixture must be aseptically removed from the device or system and added to standard culture broth in order to promote growth of the bacteria. The resin, with its absorbed antibiotic, is then discarded. Thus, the use of such a device requires several process steps, including two aseptic transfers, which makes its usage less practical.
An additional disadvantage of the before discussed device is that the resin utilized therein reduces the yield of certain bacteria. Research has indicated that the resin has a direct effect on the growth of Streptococcus (Group A) bacteria and Escherichia coli, two organisms readily sought to be isolated and identified by practioneers. Hence, the resin has a number of practical limitations.
A modification of the device and system disclosed in the U.S. Pat. No. 4,145,304 patent process has been developed by Johnston Laboratories, Towson MD. This modification concerns the addition of the resin directly into the culture medium used for the isolation of bacteria. While this modification eliminates the several step limitation of the concerned system, it does not eliminate the effect of the resin on the growth of some bacteria whose identification and isolation is quite crucial to the control and treatment of certain diseases.
In an attempt to overcome the foregoing difficulties, applicant has discovered that supplementing the bacterial growth medium inoculated with a body fluid specimen suspected of containing bacteria with antibodies specific against various bacterial inhibitors, has many advantages over conventionally known methods of isolating and identifying bacteria in body fluid specimens. Applicant's apparatus and method utilizes specific antibodies to neutralize various bacterial inhibitors present in a body fluid specimen, thereby allowing for the growth of otherwise sensitive bacteria. The antibodies react specifically with the bacterial inhibitors and, unlike the resin present in U.S. Pat. No. 4,145,304, do not inhibit growth of any bacteria. In addition, the antibodies utilized within applicant's invention can be kept in solution and, therefore, can easily be added to a wide variety of culture media, allowing for greater versatility than the resin utilized in the herein before discussed prior art process, which cannot readily be transferred aseptically. Accordingly, it is the primary object of the present invention to provide an improved means of rapidly determining the presence of bacteria in body fluid specimens containing bacteria inhibitors without reducing the bacteria count of the specimen.